Arterial blockages caused by the build up of plaque in the arteries, as is well known, can have grave consequences. Of particular concern to the present invention is the build up of plaque in the coronary arteries, which can reduce and eventually block blood flow through the affected vessel. When blood flow through a coronary artery is reduced, the heart muscle is deprived of oxygen, and the patient is prone to suffer angina. In severe cases of coronary artery blockage, the patient can suffer a heart attack and death.
To alleviate stenoses of the coronary arteries, modern surgical techniques have been developed that include procedures wherein a portion of a blood vessel is grafted onto the affected coronary artery. This shunts blood around the stenosis and thereby restores blood flow to the part of the heart muscle that was deprived of blood. These so-called bypass surgery techniques have become relatively safe and effective in restoring blood flow to the heart muscle through the coronary arteries. Unfortunately, bypass surgery is invasive, and can consequently require significant post-operative recovery time. Consequently, alternative techniques have been developed wherein a medical device is inserted into the blocked artery over a guide wire and advanced along the guide wire until the device is at the stenosis. Once in place in the artery, the medical device is activated to relieve the stenosis.
An example of one such medical procedure is a balloon angioplasty procedure wherein a balloon is positioned adjacent the stenosis and fluid is infused through the catheter to inflate the balloon This inflation causes the balloon to compact the stenosis to alleviate the stenosis. After the stenosis has been compacted, fluid is withdrawn from the balloon to collapse the balloon, and the balloon is withdrawn from the artery. An example of one such angioplasty apparatus is the device disclosed in U.S. Pat. No. 4,799,479 to Spears.
In addition to balloon angioplasty devices, atherectomy cutting devices have been developed which can be advanced into a blocked artery over a prepositioned guide wire to mechanically cut through a stenosis and thereby remove the stenosis. An example of such an atherectomy device is disclosed in U.S. Pat. No. 4,887,613 to Farr et al., which teaches a rotatable catheter and a hollow cutter attached to the distal end of the catheter.
Independent of the particular type of medical apparatus to be used to alleviate the stenosis, it is necessary to properly position the apparatus. To do this, a guide wire is typically used and for obvious reasons, it is desirable that the guide wire maintain its position within the artery during the particular stenosis-removing procedure. In other words, once positioned within the artery, the guide wire should not loose its position within the artery.
It so happens that in certain body vessels, such as the coronary arteries, undesirable guide wire movement relative to the vessel can result in the wire becoming completely dislocated from the vessel. The problem with coronary arteries in prepositioning a guide wire is aggravated by the fact these arteries near the heart have relatively tortuous paths. Consequently, it is extremely difficult to position these guide wires and once positioned they are difficult to retrieve.
To reduce delays in repositioning a guide wire which has become inadvertently dislocated from a coronary artery, surgical techniques have been developed wherein the guiding catheter, through which the wire has been introduced into the body, is left in the aorta during the entire medical procedure. A pathway is thereby maintained through the guiding catheter for repositioning a potentially dislocated guide wire.
Unfortunately, in the case of atherectomy cutters, the size of the cutter and, hence, the width of the swath which the cutter can make through the stenosis are limited by the requirement that the cutter be small enough to pass through the guiding catheter. As indicated above, there are good reasons why it is sometimes preferable if the guiding catheter can be removed.
The present invention recognizes the need for using a guiding catheter to position a guide wire in a vessel having a complex tortuous path. The present invention, however, also recognizes the guide wire can be so positioned without requiring that the guiding catheter remain in the vessel with the guide wire during the entire stenosis-removing procedure. In addition the present invention recognizes the need for a guide wire that can be easily removed from the blood vessel without causing damage to the vessel.
Accordingly, it is an object of the present invention to provide a guide wire which is positionable within a vessel of a patient and which can be used in conjunction with a variety of medical apparatus for removing arterial stenoses. Another object of the present invention is to provide a guide wire which is positionable within a vessel, e.g., a coronary artery of a patient, to substantially maintain its position within the vessel. Still a further object of the present invention is to provide a guide wire that is easy to use and comparatively cost-effective to manufacture.